1. Field of the Invention
The present invention generally relates to a sealed line structure for use in a process chamber for manufacturing semiconductor devices.
A claim of priority is made to Korean Patent Application 2004-32100, filed on May 7, 2004, the contents of which are hereby incorporated by reference in their entirety.
2. Description of the Related Arts
Semiconductor devices are generally manufactured through a series of manufacturing processes such as deposition, photolithography, etching, ion implantation, and polishing.
The deposition process, for example, forms a layer on a semiconductor substrate in a process chamber. During the deposition process, flow volume and pressure of process gases, internal pressure of the process chamber, and temperature of the semiconductor substrate are important process factors, which must be monitored.
In a conventional multi-purpose process chamber, a plate on which a semiconductor substrate is mounted is heated, or the plate itself emits heat so as to heat the semiconductor substrate.
In a system using a heater block, a power source is directly applied to the heater block. A thermocouple gauge, used as a temperature sensing unit, is connected to the heater block to monitor the temperature of a semiconductor substrate. U.S. Pat. No. 6,331,697, for example, discloses such a system.
On a heater block, an electrostatic chuck or vacuum chuck is adapted so that a semiconductor substrate is positioned and heated, or the heater block itself is equipped to chuck and directly heat the semiconductor substrate.
A power source to heat the heater block is usually disposed outside of the process chamber. An electric wire is connected to the heater block and disposed in a tubular shaped power line. It is important to seal the lead power source at the connection point with the process chamber. In addition to the electric wire, a thermocouple gauge, which monitors the temperature of the heater block, is also equipped together thereof. Specifically, one end of the electric wire is fixed to the heater block through a power line, while, the thermocouple line is adapted to attach or detach from the process chamber.
The interior of the process chamber must be under vacuum pressure during a manufacturing process, while the outside of the process chamber is under atmospheric pressure. If the connection point at the process chamber through which the electric wire is guided into the interior thereof has an air leak, the air leak may cause errors during the manufacturing process.
FIG. 1 illustrates a connection structure for a power line 2 connected to a heater block 1. FIG. 1 also shows a thermocouple line 3 connected to heater block 1. Both power line 2 and thermocouple line 3 are generally divided into upper and lower portions which are formed of different materials.
As shown in FIG. 1, in the central portion of power line 2 and thermocouple line 3, openings 2a, 3a are formed, through which an electric wire or a thermocouple gauge is inserted, respectively. The upper portion of the lines is covered with aluminum alloy material. The lower portion of the lines is threaded and formed of stainless material. The lines are generally shafts having a tubular shape. The upper end portions of the lines are fixed to heater block 1.
Power line 2 and thermocouple line 3 have a complicated sealing structure to maintain an airtight seal with the outside environment.
As shown in FIG. 2, the lower portion of power line 2 is exposed to the outside environment through a through-hole 4a formed in a process chamber wall 4. The lower portion of power line 2 comprises an O-ring 5, an adapter 6, a gasket 7, a bellows 8, and a flange collar 9, and together they are coupled to chamber wall 4 with a plurality of bolts 10 as shown in FIG. 3.
Power line 2 should seal the interior of the process chamber from the outside. However, air leaks occur because the upper portions of power line 2 made of aluminum alloy slowly erodes due to process gases used during the manufacturing processes, or air leaks occur due to welding defects.
Air leaks cause pressure in the process chamber to change, which creates process defects, and decreases production yield and productivity.
Accordingly, it is desirable to provide a sealing structure for a line capable of preventing air leaks.